Micromanipulation, which uses a micromanipulator to effect the techniques and science of microdissection, microvivisection, microisolation, and microinjections, is an expanding area which is generating a considerable amount of interest in the medical science field. Micromanipulators are well known in the art and there are various theoretical and actual embodiments of micromanipulators.
Micromanipulators or micropositioners are instruments of great precision with which a microneedle, micropipette, or other microtool can be positioned in the field of a microscope within the area to be worked upon. Currently known micromanipulators are instruments which range from simple rack and pinion assemblies to massive, accurately fitted ball bearing slide mechanisms actuated by precise feed screws or other devices. Other micromanipulators are lever-controlled and use coaxial knobs or handle mechanisms. Some available micromanipulators are hydraulically or pneumatically actuated or are piezo-electrically actuated. A well known micromanipulator is the Leitz micromanipulator.
A variety of procedures occurring in surgery and in biomedical research require positioning of microinstruments within a position of a few microns or less. Examples include treatments for retinal detachment, retinal vasculitis, and retinal artery and vein obstruction. Positioning such instruments for these tasks is generally achieved manually without a micromanipulator. The utility of conventional and currently available micromanipulators is limited by either an insufficient number of degrees of freedom or its bulk (i.e. size and weight). Though micromanipulators are commercially available, nearly all micromanipulators work by translation in a Cartesian system (i.e. X, Y and Z axes), and therefore, are unsuitable for intra-ocular surgical procedures or other procedures or applications that require the microtool to be constrained by a physical puncture point or some other determined point.
While Cartesian micromanipulators may provide precision and do have up to three degrees of freedom (in the hands of a skilled operator, controlled motions of well under five microns are readily available) they are nevertheless centerless. In other words, they do not work when the motion of the micromanipulator is constrained, as through a puncture hole in the eye. Thus, any displacement of the microtool tip will be accompanied by an equal displacement of every other point on the micromanipulator, which can cause trauma to the area surrounding the puncture point.
One field in which micromanipulation is of great interest and import is in the area of ocular surgery, particularly, retinal vascular diseases or vascular complications. Because vascular diseases or complications, (including conditions arising from diabetes and hypertension) account for a majority of all vision impairing conditions, there is a significant need for surgical instruments to permit direct access to retinal vessels (e.g. injection of medications directly into the retinal vessels). A system capable of microinjection into a single vessel would permit development of entirely new areas of treatment for retinal vascular disorders. However, control of the positioning of prior art micromanipulators has been limited by the ability of the surgeon to adjust the micromanipulators by hand using a system of wheels, gears and screws.
The limitations involved with currently available micromanipulators is especially acute for ophthalmologists who routinely place instruments inside the eye during surgery and frequently do so through a puncture in the sclera. In such procedures (e.g. vitrectomies), the inability of the surgeon to position the microtool tip with sufficient precision and maintain it is a serious limitation. The delicate nature and small diameter (approximately 100-200 .mu.m) of the retinal vessels requires an extremely precise micromanipulator which can direct a microtool within the eye, while being able to move the microtool with increased freedom without increased trauma to the eye.
Further, the positioning of the microtool tip should not affect the point where the instrument actually passes through or punctures the sclera to minimize trauma to the eyeball. Prior art micromanipulators are not suitable for such surgical manipulation since the motion of the microtool must be constrained by the puncture point, such as in the sclera of the eye. Consequently, there is a need for a micromanipulator which works in a spherical (i.e. goniometric) fashion, where the entire surgical instrument is constrained by and rotates about the puncture point or other fixed location.
To provide increased precision and flexibility, there is a need for a computer based system wherein the surgeon's hand movements are translated through an input device to correspond to the desired microtool tip positioning and movement. Thus, manual adjustments to a computer input device (e.g. joystick) which correspond to changes in the position of the microtool tip may be determined and performed by the computer system. Accordingly, the translation of the surgeon's hand movements to microtool tip positioning becomes transparent to the surgeon.
There is also a need to provide a micromanipulator and control system that has increased flexibility by allowing increased degrees of freedom for micromanipulation or other applications. There is further a need for a compact, lightweight, easy-to-use micromanipulator which can be used for ocular surgical procedures on the human eye, while having at least six degrees of freedom and remain versatile enough to be used on both medical or non-medical applications.
Accordingly, an object of the present invention is to provide a micromanipulator that is compact, relatively light-weight, and versatile which provides the user with at least six degrees of freedom for positioning the micromanipulator with precision and which is suitable for use in both medical and non-medical applications.
Another object of the present invention is to provide a computer system which translates a surgeon's input signals or indicia to relative movement of a microtool tip through the appropriate adjustment of a micromanipulator when the microtool is physically or otherwise intentionally constrained at a point.
Yet another object of the present invention is to provide a compact, high-precision micromanipulator system which permits a surgeon to control a micromanipulator tool centered on a single puncture point, while the adjustment of the micromanipulator to effectuate the movement and positioning of the microtool tip is performed by a computer system transparent to the surgeon.
The above-identified objects, as well as others not specifically iterated, are achieved in accordance with embodiment of the present invention wherein a device for precision positioning of a medical instrument includes a medical instrument holder for retaining a medical instrument at a predetermined angle. The device also includes instrument manipulating apparatus for supporting and positioning the instrument holder to position the medical instrument at the desired location. The instrument manipulating apparatus is mounted on a selectively moveable support having legs that are independently pivotally rotatable about a joint, such as a ball and socket joint. The moveable support is coupled to actuators for activating the selectively moveable support. An input device, which generates a positioning signal that corresponds to the surgeon's desired positioning of the medical instrument, is also included. A computer for controlling the actuators determines the correct movement of the selectively moveable support based on the electronic signal of the input device, which thereby positions the medical instrument at the correct location.